[1] CNR, INFM, Natl Res Ctr S3, I-41100 Modena, Italy
[2] Univ Modena & Reggio Emilia, Dipartimento Fis, I-41100 Modena, Italy
[3] Univ Parma, Dipartimento Fis, I-43100 Parma, Italy
[4] Univ Vienna, Inst Inorgan Chem, A-1090 Vienna, Austria
[5] Univ Manchester, Sch Chem, Manchester M13 9PL, Lancs, England